gui: make screen integer scaling optional

gameroy.toml

@@ -17,6 +17,10 @@ sort_list = "+File"
 # the initial size of the window in format WIDTHxHEIGHT
 screen_size = "768x400"
 
+# if true, the game screen will be scaled only by integer values, to keep
+# perfect pixel sizes.
+only_integer_scaling = true
+
 # if rewiding is enabled. This causes a small performance hit and higher memory
 # usge due to the constant doing of save states.
 rewinding = true

src/config.rs

@@ -107,6 +107,7 @@ pub struct Config {
     pub jit: bool,
     #[serde(deserialize_with = "screen_size_deser")]
     pub screen_size: Option<(u32, u32)>,
+    pub only_integer_scaling: bool,
     pub keymap: KeyMap,
 }
 
@@ -272,6 +273,7 @@ const DEFAULT_CONFIG: Config = Config {
     frame_skip: false,
     jit: true,
     screen_size: None,
+    only_integer_scaling: false,
     keymap: DEFAULT_KEYMAP,
 };
 

src/widget/pixel_perfect_layout.rs

@@ -1,5 +1,7 @@
 use giui::{Id, Layout, LayoutContext, MinSizeContext};
 
+use crate::config::config;
+
 pub struct ScreenLayout {
     size: (u32, u32),
     pub foward_button: Option<Id>,
@@ -43,10 +45,20 @@ impl Layout for ScreenLayout {
         let ratio = self.size.0 as f32 / self.size.1 as f32;
 
         if width / height < ratio {
-            des_width = self.size.0 as f32 * (width / self.size.0 as f32).floor();
+            let mut fraction = width / self.size.0 as f32;
+            if config().only_integer_scaling {
+                fraction = fraction.floor();
+            }
+
+            des_width = self.size.0 as f32 * fraction;
             des_height = (des_width / ratio).round();
         } else {
-            des_height = self.size.1 as f32 * (height / self.size.1 as f32).floor();
+            let mut fraction = height / self.size.1 as f32;
+            if config().only_integer_scaling {
+                fraction = fraction.floor();
+            }
+
+            des_height = self.size.1 as f32 * fraction;
             des_width = des_height * ratio;
         }